Science Friday - Rapidly Evolving Trout & Ancient Hyper-Apex Predators

Episode Date: October 24, 2023

Research shows some rapidly evolving trout are altering Wyoming's aquatic ecosystems. Plus, paleontologists pieced together a level of apex predators with no modern equivalent. In Wyoming’s Mountain Lakes, Stocked Trout Are Evolving QuicklyAnglers across the West love to fish in high, alpine lakes, and Wyoming’s Wind River Range is nearly unbeatable for this experience. Around this time of year, frost covers the tips of trees at sunrise, and there’s plenty of room along the lonesome blue waters above 10,000 feet.Those who do make the trek—which usually takes more than 15 miles of hiking—are greeted by hungry golden, brook or cutthroat trout looking to fatten up for the winter. They’ll take almost any fly, from a yellow foam grasshopper, to a Parachute Adams to a tiny ant. And the fish are often big, colorful and photogenic.But as untamed, historic and relaxing as a day on the water feels, it’s anything but natural. New research is shedding light on how the history of fish stocking has impacted alpine lake ecosystems in the Wind Rivers. In many cases, the genetics of trout have evolved rapidly, allowing them to survive in harsh mountain environments.Read the rest at sciencefriday.com. Hyper-Apex Predators: Colombian Fossils Reveal Big Reptilians Atop Ancient Marine Food ChainThe Paja Formation, located in central Colombia, is a treasure trove of fossils. The site is integral to scientists’ understanding of ancient creatures who roamed the seas during the Early Cretaceous period, about 130 million years ago.Now, paleontologists have pieced together the food chain of this marine ecosystem. Surprisingly, they found it supported an additional level of apex predators—think massive marine reptiles—for which there is no modern equivalent.SciFri producer Kathleen Davis talks with Dirley Cortés, paleontologist at the Centro de Investigaciones Paleontológicas in Colombia and PhD candidate at McGill University’s Redpath Museum, and Dr. Hans Larsson, paleontologist and professor at McGill University’s Redpath Museum. They discuss their fascinating findings, and the importance of better understanding this part of the fossil record.   To stay updated on all things science, sign up for Science Friday's newsletters. Transcripts for each segment will be available the week after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

130 million years ago, massive marine predators were at the top of the food chain. Imagine what it would take to feed an animal that has a skull of 2.5 meters long. It's Tuesday, October 24th, but just like every day, today is Science Friday. I'm Cyfry producer Kathleen Davis. The Paha Formation in Central Columbia has an incredible amount of fossils from the early Cretaceous period. Many of these fossils are from giant marine reptiles. They were so huge that there's no modern equivalent. We'll talk about that story in just a bit.

But first, guest host Swatnakrishna takes us to the mountains of Wyoming, where trout are evolving quickly. Wyoming's Wind River Mountain Range is a prime location for outdoor sports, including backcountry fishing. After some 15 miles of hiking, fishers can reach alpine lakes and find a variety of big, beautiful trout. But these fish high up in the mountains are not a natural phenomenon. Reporter Wilwaukee of Wyoming Public Media and the Mountain West News Bureau reported on the way humans have changed Wyoming's alpine lakes.

He joins me now from Laramie, Wyoming. Welcome to Science Friday. Hi, thank you for having me. So, Will, tell me about these fish. If they aren't natural, how did they get up into the Wind River Mountains? Starting in the 1800s, you know, more people are starting to move to the region and fishermen started stalking these water. with trout. The idea was, hey, it's good food. They're fun to catch, and it'll get people visiting the region and going fishing. And so people brought fish by the millions into these lakes. They really created a fisherman's paradise. It feels really natural when you're out there fishing, but it's actually, like you said, it's not a natural phenomenon. So you said it feels really natural. And you really like to fish up here, right? Set the stage for me. When I went out

and reported this story. I got to walk about 15 miles total into this bright blue remote lake. And on the way, I passed maybe five people. You know, you're really out there alone with your thoughts. And I just find it like one of the most peaceful and then relaxing experiences possible. And then you find this little hole where you see fish, you put this little fly out. And then you are sitting there and then suddenly like, boom, this fish just takes it. And it. And it's, It's just like this moment of excitement. And yeah, now that winter is coming in Wyoming, I'm a little sad that I'm going to have to wait a few months to get to go back out into the backcountry again. So do we know if these fish are affecting the larger ecosystem?

Where I went, the Wind River Range in central Wyoming, there were no fish there when humans stalked them initially. So it did impact, for instance, some frogs, some invertebrates. But in other parts of the West where fish were stocked, you know, in some cases there were other native. fish there, other trout. And in some cases, those fish were kicked out of the region. You know, essentially we have an invasive species situation. And so there's still a lot that we don't know, but we can say, you know, when humans do stuff like this, it tends to have big impacts and it tends to happen quickly as some science from the University of Wyoming found. So one really cool part of the story is that scientists have found that these fish are rapidly evolving.

Can you tell us a little bit about that? Absolutely. Researchers here at the University of Wyoming, went out into the back country of the wind rivers, just like I did here in Wyoming, and they studied the difference between trout that were stocked, you know, about 100 years ago versus fish that they find in hatcheries now. And they found that fish have rapidly evolved just in a couple of decades over time, essentially to eat their food more efficiently. You know, these are really extreme waters. They are frozen over for more than half the year.

There's not a lot of food up there. They're historically fishless, so they're not built to support fish, right? To survive, they've had to rapidly evolve. In this case, it's little parts of their gills that are basically evolving to eat plankton and other small bits of food more efficiently. So I talked with a University of Wyoming researcher, her name's Katie Wagner, about why this is significant. The idea of putting fish into these really extreme and novel environments and why watching them change over the course of a human lifetime is an exciting finding.

When I think of evolution, I think of it happening over thousands or even millions of years, right? Well, in this case, as Katie Wagner said, happened over the course of a human lifetime that we have fish that look completely different if they were stocked in the high alpine lakes of Wyoming versus something that's grown in a hatchery. I think something that's interesting to just think about the big picture here is humans are impacting biodiversity. sort of an unprecedented rate. And I think what this shows is just a little bit of hope that, although humans are doing that, there are cases where fish or other animals might be able to rapidly evolve amidst humans changing the environment. And that's exciting for me and gives me a lot of hope that life is going to be able to find a way, in the words of Jeff Goldblum, at least in some cases, even when humans put them in some pretty extreme and tough circumstances like the

high alpine lakes of Wyoming. Will, thank you so much for joining me. Thank you for having me. Will Waukee, reporter for Wyoming, public media and the Mountain West News Bureau, based in Laramie, Wyoming. Let's take a trip back in time to some 130 million years ago. The Paja formation in central Colombia is a treasure trove of fossils, helping us better understand the ancient creatures who roamed the seas during the early Cretaceous period. Now, paleontologists have pieced together the food chain of this marine ecosystem, and they found an additional level of apex predators, which are made up of massive marine reptiles. There is no modern equivalent to this.

Joining me now to tell us more about their fascinating findings are my guests. Dear Le Cortez, paleontologists at the Center of Investigations, Pesigestioners. paleontologists based in Colombia and PhD candidate at McGill University's Red Path Museum based in Montreal, Canada, and Dr. Hans Larson, paleontologist and professor at McGill University's Red Path Museum, also based in Montreal. Welcome both of you to Science Friday. Thanks for having us. Thank you. So, dear Le, let's start with some basics.

What is this paha formation and why is it so special? You know, for those of us who just aren't familiar? So the Paja Formation is a shallow marine sedimentary sequence in Colombia that has many, many amazing fossils such as plesiosaurus, ectosaurus, turtles and fish. And we are developing our main research with this material from the Paha formation. Can you give us a sense of like how big this formation is? Okay, so the Paja formation outcrops in central Colombia

and one of the richest outcrops is located in Villa where I was born and the Paja formation is quite big has many, many interesting marine reptile material

and we've been prospecting the Paja formation for many years now. And as you said, you actually grew up in the town where this fossil formation was discovered. I mean, so what does it mean for you, for your hometown to be a source of such an amazing scientific discovery? It's just a dream come through. I got a chance to work with this material from my hometown, Villa Leibah, and it's just

amazing. I think it's a big privilege for me to be able to do research there. So Hans, why is it so important to understand this marine ecosystem during this early Cretaceous period? The life that we have today, like the marine ecosystems, are pretty complex. Like we have whales, fishes, a whole cadre of animals living in the seas and create this incredibly complex ecosystem. And if you go back, let's say about 300 million years ago, it was certainly not the case. And sometime in between that, there was this phenomenon, called the Mesozoic Marine Revolution, where everything is sort of transformed into something

that we might recognize today. And the importance of looking at this site in particular is that not only is it so amazingly fossiliferous, lots and lots of specimens and high high diversity, but it's also kind of a midpoint in that trajectory. So the importance of looking at it is to see how we can start to understand how this Mesozoic Marine Revolution happened in the seas. So part of this research was looking at this food chain in this early Cretaceous period. Deerle, how does this food chain compare to modern marine ecosystems? So the power formation by Yoda is really complex, really diverse, and we have no analog for this marine ecosystem. So modern ecosystems, such as the Caribbean system, has a.

up to six traffic levels, but the PAHA formation may have had even seven or more. So one more traffic level happening at the top of the food chain. So in terms of ecosystem structure, we have some similarities, but the top of the chain is completely different between these two ecosystems. So I'm really interested to learn more about these huge marine reptiles that were at the very top of this food chain. Dirlay, can you tell me a little bit about these creatures? Yeah, so these were the scariest marine reptiles ever. So we have in this ecosystem, pleasosaurs, ectosaurs, fish, sharks, crocodilimores.

So these were large-bodied marine reptiles. or marine vertebrates, and they were living or interacting with each other in ways that we don't comprehend quite well, but we are exploring how this ecosystem may have looked like bugging in time. So since we don't have any analog for these marine organisms, this is just a good opportunity to look at complexity and stability for these marine ecosystems. I want to learn a little bit more about these terrifying marine reptiles. I mean, help me imagine them. Did they all look kind of similar? Were they all different? So the pleasurs, they were of two kinds, one, which is the short-necked pleisors,

which were really scary, huge, and they had these really large. And they had these really large. teeth and the other type are the elasmosaurus with a really long neck and then we have the ectiosaurus which were like a tuna shape marine reptile so we discovered this large teliosaur which is a polym marine crocodile morph with about 10 meters in length 10 meters in length 10 meters in length is very long for what I imagine was a very scary looking creature Hans, how does this extra level of the food chain affect the rest of the ecosystem? This extra level of food chain, it affects it because it's adding this level of complexity that we just don't see today. And so imagine what it would take to feed an animal that has a skull of 2.5 meters long, teeth the size of your hands.

And they're feeding on organisms that are probably smaller than them, but not much smaller because their skulls are just so enormous. and their prey has been feeding on something else, which is also pretty large by today's standards. And you can just keep on walking down that food chain. And what you come up with is this incredibly rich and complex ecosystem that is supporting these enormous sort of hyper apex predators that we just don't have today. Are there things missing from that ancient food chain that we have now?

So it turns out that in constructing this food web and then comparing it to something that we thought would be a pretty good analog, a natural Caribbean marine food web, turns out we're missing almost everything. So almost all of the medium to small fishes, almost all of the ground dwelling or benthic invertebrates, they're not in the fossil record yet. Every time a piece of something in that category is found,

it turns out to be a new species in that formation. And so I think it's just going to take a little bit more time, maybe a few more generations of fossil hunting, to really flesh out the rest of this ecosystem. So you think that they did exist, but we just haven't found evidence of them. Is that right? I think that's right.

And the reason why I'm quite sure of that is that other formations from different continents, but around the same time, do preserve these kinds of animals. And so it's just a matter of time until we can find that in this particular formation, which is always a problem of paleontology because there's always going to be some kind of bias,

usually because the fossils aren't preserved the same way, or maybe the paleontologists don't have the same eye for it. If you're walking and you cross by a two and a half meter skull versus a little two centimeter crab, what are you going to find the first? Right. More exciting probably to find the several meter skull. And so another interesting thing about this work is that you found so many different species of ammonites, which are these extinct mollus creatures.

Can they help us better understand this ecosystem? The ammonites in the Pahaan formation are world famous. There's over 100 species in this formation. You cannot walk in places without stepping on ammonite. It's that rich. But we have no analog today. The closest thing would be something like the Nautilus, which only superficially looks like ammonites.

And these ammonites were probably quite diverse in their ecology. Some may have been filter feeding, some may have been predatory, some may have been scavenging, but they're everywhere. That might be something that is really unique to the system. It might be thriving this sort of intense food web. What they do is they fill in. We discovered kind of like a middle tier of the food web. And so they're feeding on something probably quite rich underneath them.

And they're also providing something quite rich in terms of their predators about them just because of their amazing diversity. So sequencing this food chain, I would imagine, is kind of just, one piece of this puzzle of understanding this formation and this ancient ecosystem. Duley, what are the questions that you hope to answer next? So we know what is missing in the paja, and so we don't know exactly why. So lower levels in the food chain are missing, and it would be really interesting to explore what is specifically is what is going on at the base.

of the food chain in terms of toponomy, in terms of biodiversity, and in terms of ecological structure to be able to support higher trophic levels. So that would be one interesting question. And another would be how energy is distributed throughout the system. So there are plenty of questions we are asking now, but we just need more prospecting to be able to do so. Hans, any questions that you are hoping to find the answer to in the future? That's a loaded question. I think what this does is it sort of just exposes the tip of the iceberg on what's possible here. And so while the Paha formation is an intensely rich and exciting fossil deposit,

and D'Urlet was talking about how that could be expanded and we just keep on going further and further in that one formation, we can start looking also around it, both geographically around it and stratigraphically. above and below it. And think about how these really intensely complex ecosystems came to be that way and why they aren't like that anymore. Well, that is all the time that we have for now. I would like to thank my guests. Dear Le Cortes, paleontologists at the Central de Investigations, paleontologists based in Colombia, and also a PhD candidate at McGill University's Redpath Museum based in Montreal, Canada. and Dr. Hans Larson, paleontologist and professor at McGill University's Red Path Museum, also based in Montreal.

Thank you both so much. Thank you. Our pleasure. Thank you. And that's it for today. A lot of folks helped with today's show, including Jordan Smudjik, Charles Bergquist, George Harper, John Dancosky, and many more. Tomorrow we'll take a look at NASA's mission to an asteroid made of metal. We'll catch you then. I'm Kathleen Davis.